The present invention is related to the field of cargo handling, and more particularly, to a conveyor assembly system and method of use for efficiently moving cargo containers in or from a ship to the backlands of a container terminal, where the containers can either be stacked for storage or loaded on trucks or trains for land transport.
Maritime container terminals are faced with a high volume of traffic, limited land, and ever increasing vessel size. Efficient unloading/loading of ISO containers, their storage, and their retrieval, is critical to the successful running of a maritime terminal.
Containers arriving by sea to a conventional terminal yard are removed from ships by massive Ship To Shore (STS) cranes that place the containers on yard transporters, which transport the containers to and from the ship load/unload site and to/from the stacking/storage area. An inventory of two-weeks or more can be stored in a yard, wherein containers are stored in blocks (e.g. a storage block of length of 10, width of 6, and height of 4 or 5 containers). Gantry cranes are then used to “dig-out” containers on lower levels of the storage blocks, moving the containers to either highway trucks, railroad cars, or back of yard transporters for return to the ship. This process of loading and unloading a vessel, and the movement of the ISO containers around the terminal yard is cumbersome and time intensive.
Without exception container terminal throughput has been limited by backland operations rather than by STS Crane productivity. For decades, experienced container terminal planners have recognized that fact but have yet to design a major terminal with backland productivity that can fully match peak STS productivity.
At first glance direct transfer from ship to train rail seems a logical way to go. However, rail cars do not fit ship hatch and the STS crane spacing that must align with ship hatches. Even if they did fit, the train of rail cars would move as a unit so the productivity of a fleet of four or five cranes would be limited by the slowest individual crane unless every crane had its own dedicated rail line.
A conventional conveyor similar to what is used for bulk cargo eliminates the hatch spacing issue but containers cannot be loaded or unloaded from a moving conveyor. Again, for a fleet of cranes the slowest crane would set the fleet productivity unless every crane had its own dedicated conveyor.
In an attempt to increase productivity, container terminals can also employ automated yard transporters called automatic guided vehicles (“AGV”), and in the some of the world's most technologically advanced maritime terminals the AGVs feed ISO containers to automated storage and retrieval systems (“AS/RS”). For most container terminals complete automation is not financially feasible. In addition to cost, when AGVs are employed in a yard no human traffic is allowed on the yard due to safely concerns, and the yard must be paved and accordingly provided with a adequate drainage system for smooth operation of the AGVs.
It would be advantageous to provide an improved cargo handling system that obviates the aforementioned storage and stacking logistical problems in a cost effective manner.